1. Field of the Invention
The present invention relates to a clamping fixture that clamps a printed circuit board to a vibration table.
2. Description of Related Art
Electronic card assemblies typically contain a number of integrated circuit packages soldered to a printed circuit board. The solder joints of the IC packages must be capable of withstanding shock and vibration loads. To test the structural integrity of an electronic card assembly, the electronic card is typically mounted to a shock/vibration table. The vibration table is constructed to exert shock and vibrational forces onto the card. Relative movement between the electronic card and the table may distort the resultant energy curve of the card. To prevent movement between the card assembly and the table, the edges of the card are therefore secured by some type of mounting fixture.
U.S. Pat. No. 5,014,000 issued to Schlagheck discloses a vibration table assembly which has a mounting fixture that can secure a plurality of printed circuit boards to a vibration table. The fixture has a center metal block which contains a plurality of grooves located on opposite sides of the block. Spaced from each side of the center block are a pair of outer blocks that also have a plurality of grooves. The ends of the printed circuit boards are inserted into corresponding grooves and held in position by the blocks. The blocks are mounted to the vibration table by a number of bolts that screw into corresponding holes in the table. The table has a number of holes that allow the outer blocks to be moved relative to the center block, to compensate for circuit boards that have different lengths.
The grooves of the Schlagheck fixture are fixed and can only accept circuit boards that all have the same corresponding thickness. Therefore to test thicker boards a new mounting fixture must be assembled to the table. Dismounting the fixture and assembling a new fixture increases the test time and ultimately the overall cost of the test. Additionally, the mounting fixture of the Schlagheck table has a relatively large mass and a corresponding low resonant frequency. If the frequency range of the vibration load extends into the resonant frequency of the mounting fixture, the fixture will distort the energy curve of the table. It would therefore be desirable to provide a mounting fixture for a vibration table that has a high resonant frequency and can easily compensate for circuit boards that have varying dimensions.